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Homework Help: Find the derivative an determine the values

  1. Oct 5, 2005 #1
    Suppose [tex] f(x) = \frac{(x-3)^{4}}{x^{2}+2x} [/tex]. Find the derivative an determine the values for which it is equal to 0. So [tex] f'(x) = \frac{x^{2}+2x(4(x-3)^{3}) - (x-3)^{4}(2x+2)}{(x^{2}+2x)^{2}} [/tex]. But now how would I go about finding the values for which the derivative equals 0? [tex] f'(x) = \frac{x^{2}+2x(4(x-3)^{3}) (x-3)^{4}(2x+2)}{(x^{2}+2x)^{2}} = 0 [/tex]. Is it possible to factor?

    Thanks
     
  2. jcsd
  3. Oct 5, 2005 #2
    For any fraction, let's call it [itex]\frac{A}{B}[/itex], which part will make the whole thing equal to 0? A or B?
     
  4. Oct 5, 2005 #3
    A

    will yeah
     
  5. Oct 5, 2005 #4

    BobG

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    You missed a set of parentheses.
     
  6. Oct 6, 2005 #5

    TD

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    Your derivative isn't correct yet, make sure you check that first!
     
  7. Oct 6, 2005 #6

    HallsofIvy

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    The derivative is correct, assuming that the missing parentheses BobG mentions is put in correctly!
     
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